With a processed manufactured product like a crank shaft or a cam shaft or the like, sometimes convex flaws such as traces of blows during processing are present at locations such as journal portions, pin portions, cam portions or the like at which high accuracy surface processing has been performed. It is necessary reliably to discover and to eliminate manufactured products upon which such flaws are present by inspecting them. Thus, in the prior art, testing by visual inspection has been performed upon all the products by hand.
Now, in Japanese Laid-Open Patent Publication Heisei 11-83413, there is disclosed a device which automatically measures the diameter, the roundness, the straightness, and the like of a journal portion or a pin portion by, in a state in which a contactor which can shift in the direction vertical to the rotational axis of a crank shaft is contacted with a constant force against the outer circumferential surface of the journal portion or the pin portion of the crank shaft, measuring the displacement of this contactor in each angular rotational position while rotating the crank shaft.